Stoker feed mechanism



Oct. 10, 1944. c, R, BARR 2,359,742

STOKER FEED MECHANISM Filed Sept. 17, 1940 4 Sheets-Sheet l Iii/ 2 c. R. BARR STOKER FEED MECHANISM Oct. 10, 1944.

4 Sheets-Sheet 2 Filed Sept. 17, 1940 mm A EW a INVENTOR.

Oct. 10, 1944. c. R. BARR STOKER FEED MECHANISM 4 Sheets-Sheet 3 Filed Sept. 17, 1940 INVENTOR.

Oct. 10, 1944. c. R. BARR STOKER FEED MECHANISM Filed Sept. 17, 1940 4 Sheets-Sheet 4 INVENTOR.

Patented a. 10, 1944 UNITED STATES PATENT OFFICE 2,359,742 STOKER FEED MECHANISM Charles R. Barr, Allison Park, Pa.

Application September 17, 1940, Serial No. 357,127

3 Claims.

This invention relates to new and useful improvements in stokers and it is among the objects thereof to provide a stoker adapted for feeding a proper quantity'of coal properly distributed over the fire bed at a proper time to obtain maximum efliciency of combustion throughout the fire box area. 4

The invention will become more apparent from a consideration of the accompanying drawings constituting a part hereof in which like reference characters designate like parts and in which:

Fig. 1 is a rear elevational view of a stoker feed apparatus embodying the principles of this' invention;

Fig. 2 a side elevational view thereof Fig. 3 a rear elevational view of the main frame structure for supporting and housing the feed mechanism;

Fig. 4 a side elevational view of the stoker frame;

Fig. 5 a horizontal cross-section partially in elevation taken alongthe line 5-5, Fig. 4;

Fig. 6 a top plan view diagrammatically illustrating the directional path of the fuel as distributed by the stoker feed mechanism;

Fig. 7 a vertical cross-section partially in elevation of a fire box and the stoker mechanism;

Fig. 8 a top plan view of an adjustable crank;

Fig. 9 a vertical section thereof taken along the line 9-9, Fig. 8;

Fig. 10 a vertical section partially in elevation of the crank of Fig. 8 taken along the lines Ill-I0, Fig. 8; and

Fig. 11 a cross-section of the friction feed drive taken along the line H-l i, Fig. 2.

With reference to Figs. 6 and 7 of the drawtions, as shown in Fig. l, with successive sections staggered, as shown in Fig. 7. The shaft 1 is driven by a pawl ancl ratchet mechanism. Figs. 2 and 11. The shaft 1 is keyed at 8 and 9, Fig. 11, to a pair of conically shaped friction disks Ill and I l which coact with a ratchet wheel l2 having teeth l3 that are engaged by a pawl M, the contact between the friction disks l0 and II and the ratchet wheel I! being adjusted by means of the nut I5 on the end of shaft 1.

Suitable clearance I6 is provided between the conical disks and the ratchet wheel to assure ings, it is the primary object of the stoker feed mechanism to distribute the coal or coke over the fire bed uniformly throughout the length and breadth thereof, the arrows in Fig. 6 illustrating the path of the coal as it leaves the stoker, which may be generally designated by th numeral I. I

Fig. 7 demonstrates the horizontal path of the coal as it leaves the spreader apron 2 of the stoker, the numeral 3 designating an evenlydistributed bed of coal on a stationary grate or hearth 4. The distribution of the coal over the fire bed, as shown in Figs. 6 and '7, is effected by means of the following mechanism;

The coal is placed in a hopper 5, Fig. 7, and is fed by gravity into the path of a plurality of paddles 6 mounted on a square drive shaft 1, the paddle conveyor being constructed in seccontact of the conical surfaces of the engaging members. The purpose of the friction drive is to avoid damage to the feed mechanism, particularly the paddle conveyor 6 if a large piece of slate or other foreign element such as iron bars or spikes are fed from the hopper to the paddle conveyor. If, for example, an iron bar would become lodged in the paddle conveyor, the feed mechanism, including the ratchet drive, would continue to operate without revolving the conveyor shaft 1. To dislodge the obstruction, pawl i4 is disengaged and shaft 1 shaken back and forth by means of lever la.

As shown in Figs. 2 and 11-, pawl I4 is pivotally mounted on a crank I! that is pivoted on the drive shaft 1. The crank I1 is connected by a link l8 to a lever 19 that is pivoted at 20, the other end of the lever being connected at 2| to a. link 22, one end of which is mounted on an adjustable crank pin 23. Crank pin 23 is driven by shaft 24 that is coupled to a variable speed transmission generally designated by the reference character 25,'and which may be of the type employed in automotive vehicles having a shifting lever 26, as shown in Fig. 1. Transmission 25 is coupled to a gear reduction mechanism gener ally designated by the numeral 21 that is driven by an electric motor 28 or any other suitable prime mover.

It is to be noted with reference to Fig. 1 that the stoker frame maybe constructed of a onepiece steel casting to which all the operating parts are rigidly connected ,to provide adequate support and the drive mechanism is of rugged construction to eliminate wear on the operating parts. The coal may be fed at a rate suitable for the particular requirements by the speed change transmission 25 and by adjustment of the crank pin 23 which is effected by the structure shown in Figs. 8 to 10 inclusive. The numeral 29 designates a hub shaped disk which is mounted on the transmission shaft 24 to rotate therewith. The face of the disk at the center The crank pin may be set in any of the slots of the drive disk 29 to vary the thrust in accordance with the desired rate of feeding through the pawl and ratchet mechanism. To effect the adjustment, it is necessary to remove the clamping plates 32, remove the crank pin 23 from the slots 30 and place it in its adjusted position. The clamp plates 32 are then inserted in the slots of pin 23, as shown in Fig. 9, and the crank pin is held against movement by the interacting teeth of the pin and drive disk. It is apparent that a wide range of feed adjustment is provided through the transmission 25 and the adjustable crank pin to obtain any desired rate of feeding the fuel to the fire box.

Distribution of the coal after it is delivered by the paddle conveyor 6 to the spreader apron is effected by a plurality of blast nozzles 35, Fig. 7, one end of which communicates with a steam box 36 and the other end with flared grooves 31 of the apron 2, Fig. 5. The steam or blast emitted by the several nozzles may be separately regulated by a needle valve 38 having a stem extending through a strap 39, each valve stem being provided with a grip 40 to effect adjustment of the. blast emitted from the nozzles 35. The sides of the apron 2 are provided with flaring blades 4| to permit distribution of the fuel at the front end of the fire box. Steam or compressed air is supplied to the chamber 36 through a conduit 42, and one end of the chamber is plugged at 43, The nozzles 35 may be adjusted to distribute the fuel over any size fire box and the pressure regulated to distribute the fuel throughout the length of the fire box.

The operation of the stoker feed mechanism is briefly as follows: The stoker is clamped to the charging opening of the furnace, as shown in Fig. '7, and the hopper 5 is charged with coal which, because of the efficient combustion obtained by the distribution of the fuel in the fire box, may be of an inferior grade. Motor 28 is then energized and the shifting lever 26 is moved to the desired speed position. Power is transmitted through transmission 25 to the shaft 24 to rotate the drive disk 29 which revolves to actuate crank pin 23 which has been set on the drive disk 29 to exert a predetermined angular thrust on lever l9 through the connecting link 22. As the lever l9 oscillates, the pawl housing I1 is subjected to oscillating movement which in one direction causes pawl M to engage the teeth of ratchet wheel l2, which in turn rotates the square shaft 1 of the paddle conveyor 6. As the conveyor 6 revolves, coal is fed to the apron 2 in the path of the steam jets 35 and is lifted from the apron and distributed over the fire box area, as shown in Figs. 6 and 7. By proper adjustment of the needle valves 38, the necessary amount of blast is obtained to provide for a uniform distribution of coal over the entire hearth invention to the use of steam boilers of all sizes and capacity and also gives to each individual boiler a wide capacity range.

The use of the speed transmission 25 coupled with the feed adjustment of the panel conveyor permits rapid change of the rate of fuel feed in accordance with the needs of the boiler, for example, if the boiler is rated 100 H. P, and the fuel consumption is 8 pounds per H. P. per hour, the adjustable crank 23 may be set to feed 800 pounds of coal per hour with the transmission 25 set for normal feeding speed. By shifting lever 26 to either increase or decrease the transmission speed, the fuel feed may be correspondingly increased or decreased to get double or half the coal feed capacity to meet any particular operating requirements.

The apparatus is durable and compact and takes up very little space at the charging end of the furnace.

Because of the even thickness of the fuel bed, it is possible with proper aeration of the grate to burn slack or the waste product of coal mines without the formation of clinkers.

Although one embodiment of the invention has been herein illustrated and described, it will be evident to those skilled in the art that various modifications may be made in the details of construction without departing from the principles herein set forth.

I claim:

1. In a materials feeding and distributing mechanism, an apron for receiving and distributing the material, a conveyor for feeding the material progressively from one side to the other side of said apron, drive mechanism for subjecting said conveyor. to intermittent movement to feed successive charges of measured volume to said apron, and a divergent blast impinging upon said apron arranged to distribute the material forwardly and longitudinally of said apron.

2. In a materials feeding and distributing mechanism, an apron for receiving and distributing the material, a paddle wheel conveyor having a plurality of axially aligned paddles with the blades of adjacent paddles angularly spaced progressively from one side to the other sothat when rotated the blades of adjacent paddles successively push a measured quantity of the material progressively from one side to the other side of the apron, drive mechanism for subjecting the paddle wheel conveyor to intermittent movement, and a :blast intermediate the conveyor and material arranged to impinge upon the apron to distribute the same forwardly and longitudinally of said apron.

3. In a materials feeding and distributing mechanism, an apron for receiving and disof the fire box to an even thickness to produce tributing the material, a paddle wheel conveyor" having a plurality of axially aligned paddles with the blades of adjacent paddles angularly spaced progressively from one side to the other so that when rotated the blades of adjacent paddles successively push a measured quantity of the material progressively from one side to the other side of the apron, drive mechanism for subjecting the paddle wheel conveyor to intermittent movement, and a plurality of laterally spaced nozzles above the said apron directed to impinge upon said apron for directing a divergent blast forwardly and longitudinally of said apron.

CHARLES R. BARR. 

